1. Field of the Invention
The present invention relates to a method for informing charging data to a mobile terminal in a code division multiple access (CDMA) type or a time division multiple access (TDMA) type mobile radio communication system which enables a mobile terminal subscriber to immediately confirm, via his/her mobile terminal telephone, charge status that is calculated and managed by a charging center.
2. Description of the Related Art
Mobile communication system technology is widely used by individuals, automobiles, ships, trains, airplanes, etc. Specifically, the mobile communication system includes mobile telephones, such as portable telephones or telephones for vehicles, harbor telephones, telephones for airplanes, and mobile public telephones installed in the excursion ships, the express buses, etc. The mobile communication system also includes radio pagers, radio telephones, satellite mobile communication devices, amateur radios, fishery radios, etc. The advanced mobile phone service (AMPS) system is an analog type mobile communication system. In contrast, the CDMA and TDMA systems are digital type mobile communication systems.
FIG. 1 is a block diagram illustrating the construction of a conventional mobile radio communication system. Referring to FIG. 1, a mobile communication exchange 120 performs exchange functions and interacts with another mobile communication exchange. The mobile communication exchange 120 connects with a different communication network, such as a PSDN, and also controls a call termination/origination of a mobile terminal 100. In addition, the mobile communication exchange 120 informs the charging center 130 of charging information, such as a subscriber number, terminating number, call start time, call termination time, discount information and so forth, when the call is terminated in the mobile terminal 100. The charging center 130 calculates and manages telephone charges to provide the necessary charging information. For example, if thirty days elapse, the charging center 130 calculates an accumulated telephone charge for the calls made during the 30-day period for each mobile terminal subscriber, and notifies the respective mobile terminal subscriber of the total charge. A basic charge and a tax charge are added to the total telephone charge in the form of a bill 150.
According to the conventional mobile communication system described above, it can not know the call charge just after a mobile terminal subscriber terminates a telephone call. Also, there is no means for the mobile subscriber to instantly find out the current total telephone charge.
In order to solve the above problem, a mobile terminal having a built-in charging device has been developed. This charging device obtains call time information (i.e., call start time and call termination time) using a timer (not illustrated) provided in the mobile terminal. Typically, the timer is used to inform the mobile terminal subscriber of the call time through an output device (for example, a liquid crystal display) of the mobile terminal.
The timer starts its operation at the pointer of time when the mobile terminal detects a ring back tone transmitted to the mobile communication exchange, but there is a discrepancy between this time and an actual telephone call time. Thus, the telephone charge calculated by the charging device has an error in comparison to the telephone charge actually imposed on the mobile terminal subscriber by the vendor. Also, since the discount rate may be different according to the type of service enrolled in by the subscriber, an accurate telephone charge can not be known when such a discount rate is not considered. Furthermore, since the real bill contains a basic charge, a tax charge, and other charges not available till a subscriber receives the bill after, for example, 30 day billing cycle, the prior art mobile phone having the built-in timer does not given an accurate billing charge report.